Trust & transparency

Sources & References

Every figure on GreenCalcs traces to a primary, authoritative source. This page lists the government, national-laboratory and industry references behind our calculators and guides, organized by topic, so you can verify any claim yourself.

SCMaintained by Sarah Chen, Energy Analyst Primary sources: IRS, DOE, NREL, EIA, DSIRE, EPA
Why this mattersWe don't cite installer marketing — we cite the source. Tax rules come from the IRS, incentives from DSIRE, electricity rates from the EIA, costs and reliability from NREL, and heat pump data from the DOE and ENERGY STAR. See how we use them in our methodology.
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Federal tax credits & the IRA

  1. IRS — Residential Clean Energy Credit (25D)
  2. IRS — Energy Efficient Home Improvement Credit (25C)
  3. IRS — Form 5695 & Instructions
  4. IRS — Alternative Fuel Vehicle Refueling Property Credit
  5. U.S. Dept. of Energy — Home Energy Rebates (HEAR / HEEHRA)

State & local incentives

  1. DSIRE — Database of State Incentives for Renewables & Efficiency
  2. EPA — Solar for All
  3. ENERGY STAR — Rebate Finder
  4. U.S. Dept. of Energy — Low-Income Community Energy Solutions

Solar performance, technology & reliability

  1. NREL — Photovoltaic Research
  2. NREL — PV Module Reliability
  3. U.S. Dept. of Energy — Homeowner's Guide to Going Solar
  4. U.S. Dept. of Energy — SolarAPP+ Instant Permitting
  5. U.S. Dept. of Energy — Solar Energy & the Circular Economy
  6. EPA — Solar Panel Recycling

Heat pumps & home heating

  1. U.S. Dept. of Energy — Heat Pump Systems
  2. U.S. Dept. of Energy — Air-Source Heat Pumps
  3. ENERGY STAR — Heat Pumps
  4. NEEP — Cold Climate Air-Source Heat Pump List
  5. CEE — Residential Heating & Cooling Specifications
  6. EPA — Section 608 Refrigerant Handling

Electricity prices & energy data

  1. EIA — Electricity Data
  2. EIA — Electric Power Monthly
  3. NREL — Solar Resource Data & Tools

Consumer protection & safety

  1. Federal Trade Commission — Solar Power for Your Home
  2. NFPA / National Electrical Code
  3. FEMA — Building Resilience
Related

How we use these

Our Methodology →

How we turn these sources into calculators and guides.

Guides →

40 in-depth guides, each citing its own sources.

Glossary →

Plain-English definitions of the technical terms.

See the data put to work

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